Goodwill (Schedule of Goodwill by Segment) (Details) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018
Goodwill [Roll Forward]
Goodwill, net, beginning balance	$ 788.9	$ 721.5
Acquisitions	48.6	78.0
Currency translation and other	(40.4)	(10.6)
Goodwill, net, ending balance	797.1	788.9
Industrial Gases - Americas
Goodwill [Roll Forward]
Goodwill, net, beginning balance	162.1	163.7
Acquisitions	0.0	0.0
Currency translation and other	(5.8)	(1.6)
Goodwill, net, ending balance	156.3	162.1
Industrial Gases - EMEA
Goodwill [Roll Forward]
Goodwill, net, beginning balance	424.4	402.4
Acquisitions	38.5	29.5
Currency translation and other	(30.6)	(7.5)
Goodwill, net, ending balance	432.3	424.4
Industrial Gases - Asia
Goodwill [Roll Forward]
Goodwill, net, beginning balance	171.9	135.2
Acquisitions	10.1	38.1
Currency translation and other	(3.5)	(1.4)
Goodwill, net, ending balance	178.5	171.9
Industrial Gases - Global
Goodwill [Roll Forward]
Goodwill, net, beginning balance	20.1	20.2
Acquisitions	0.0	0.0
Currency translation and other	(0.5)	(0.1)
Goodwill, net, ending balance	19.6	20.1
Corporate and other
Goodwill [Roll Forward]
Goodwill, net, beginning balance	10.4	0.0
Acquisitions	0.0	10.4
Currency translation and other	0.0	0.0
Goodwill, net, ending balance	$ 10.4	$ 10.4

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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